A beta cell contains about 10 000 secretory granules. Of these, about 1000 are docked at the inner surface of the plasma membrane and a subset of about 100 docked granules form the "readily releasable" pool (granules which are released within about 5 minutes of glucose stimulation). As inferred from rat MIN6 cells, docking occurs by interaction between EXOC3/Sec6 located on the membrane of the secretory granule and EXOC4/Sec8 located at the plasma membrane (Tsuboi et al. 2005). Additional components (EXOC1, EXOC2, EXOC5, EXOC6, EXOC7, EXOC8) form the Exocyst Complex. EXOC7 binds the plasma membrane (Matern et al. 2001).